1. Field
The invention pertains generally to collapsible shelters of the umbrella-tent type. In particular, the invention relates to a portable shelter, including a foldable frame with the shelter cover, i.e., canopy, affixed thereto, which is adapted for quick, easy erection from its folded, compact form and vice-versa.
2. State of the Art
In recent years, backpacking has become very popular, and portable, single unit tents, which have the frame and canopy incorporated into one unit and can be folded into a compact, lightweight package, have been provided to take the place of the older, more cumbersome tents in which a frame and canopy are separable from each other. A sturdy, lightweight, foldable quickly erectable and collapsible shelter of the umbrella type is disclosed in U.S. Pat. No. 3,794,054, issued to Paul J. Watts on Feb. 26, 1974. In accordance with the disclosure of that patent, a frame and canopy are provided in a single unit wherein the material of the canopy is held loose on the frame when the shelter is in a collapsed position and taut on the frame when the shelter is in an erected position. In addition, the central pole of conventional umbrella-type tents was eliminated, with the shelter retaining all the structural stability of such umbrella tents having a central pole.
The frame of the shelter disclosed in U.S. Pat. No. 3,794,054 includes a vertical erecting rod located at the apex of the frame. The erecting rod is adapted to slide up and down through a central hub which forms the apex of the frame. A plurality of flexible, segmented support members are pivotally attached to the central hub, and an equal number of rib members are pivotally attached at mutually respective ends to the support members. The other ends of the rib members are pivotally attached to a second hub which is mounted on the erecting rod below the central hub, so that when the second hub is moved into proximity of the central hub, the support members assume a position extending outwardly and downwardly from the central hub with the cover or canopy tautly affixed thereto, and the rib members extends substantially radially outward from the second hub. In the erected position, the second hub has a resultant force acting thereon which tends to hold it against the central hub due to an over-center type action achieved by raising the second hub to a position such that the rib members pass the equilibrium position perpendicular to the erecting rod and slant slightly upward towards the center of the tent. However, it has been found that inadvertent, undesired downward movement of the second hub, with the resulting untimely collapse of the shelter, can occur under certain circumstances in normal use of the shelter. For example, the shelter is subject to untimely collapse under cetain wind conditions which cause depression of the apex of the shelter.